Vegetarian or vegan? A choice concerning not only you

With a growth rate of 1.5 percent in 15
years, in 2014 Italian vegetarians and vegans are about 4 million, according to
Eurispes report. Vegetarians avoid eating
meat, while vegans follow a stricter regime with the absence not only of meats,
but also of products originated from animals. After centuries of omnivorous diet,
may these new habits have consequences or benefits for our body?

Inside the human guts, there is a huge
microbial ecosystem. The interest around human intestinal or oral microbiota,
namely the commensal bacteria that we house in our guts, has quickly increased
over the last years: in fact, the number of Pubmed cited publications about
this topic has raised from 80 issues in 2000 to 2,700 in 2013. The reason lies in the involvement of gut bacteria in different physiological
or pathological conditions, ranging from energy
regulation, cognitive processes and immunity trade-off.

Despite the big number of studies
about microbiota, “there are few observational studies considering the faecal
and salivary microbiota, and metabolome of individuals subjected to different
dietary habits since long time ago”, said Marco Gobbetti, leader of Diet4MicroGut, an Italian project arisen to investigate the bacterial flora
susceptibility to diet, and the relationship between microbiota alteration and
state of well-being. Since nutrients for humans are nourishing
able to affect the growth and balance of native microbes, an impaired diet may
imbalance the gut flora and, as Gobetti explained, “we still don’t know if the
genetic heritage may be (and to what extent) a lifeline towards a wrong diet”.
In fact, other studies are based on the effects of rapid and intense change of
the dietary habits, and alterations of the human intestinal and salivary
microbiota over a short time has been already observed.

In order to study how the omnivore,
vegetarian and vegan diets may affect the oral intake of microorganims, and the
composition of the oral and faecal microbiota, the research has been addressed
to a large number of individuals (about 50 for each dietary condition),
recruited in various Italian regions. “It's the first time that a microbiota
research has been addressed to such a large number of individuals”, said
Gobetti and his words are confirmed by the inclusion of the Italian study in
the U.S. clinical trials list. Dietary habits registration and biological sample collection covered three
weeks, then samples have been analysed in ten Italian research centres, joined
in a unique effort to build up a permanent European platform for such type of
studies.

Researchers are analysing samples with a
huge variety of techniques: bacteria will be recognized and characterized for
their antibiotic resistance, for DNA sequences and functional activities, and
for metabolomics traits, with the aim to determine representative populations
of the three types of diet. Diet4MicroGut has started in 2013 and it
will go on until 2016. The first results are about the salivary microbiota.
Analysis from the Ercolini's laboratories at Federico II University in Naples
confirmed that dietary habits seem to slightly influence the microbial
composition and only in part the metabolome. “The faecal microbiota could
represent another issue and we hope to get some consistent results within the
next months”, said Gobbetti.

The interest for Gobbetti's
group research is strengthen by some new findings. Cathryn Nagler has recently
published a paper on PNAS, underlying the
role of gastrointestinal bacteria in allergic response to food. The absence of
specific bacteria could be detrimental for some immunological reactions
responsible for allergies. In addition, the author suggested that an ultimate
solution could be the allergy process interruption by manipulating the
microbiota. Moreover, the Martin Blaser paper, appeared on Cell, showed how
microbiota alterations are related to obesity and how could be important to
restore the balanced gut population. Finally, another study
published on Nature compared the
Italian diet with that of African hunter-gatherers Hadza, confirming how diet
could influence guts populations but also health: for instance, Hadza do not
suffer from colon related diseases. Starting from these premises, it could be
interesting to assess if different diet are able to restore or conserve guts
flora.

Gobbetti’s team
research is destined to rise: “we are already involved in a European joint
project initiative (ENPADASI) that aims to establish a European network among
research groups working on diet and human body responses in health and disease
states”. Gobbetti also highlighted
the possibility to go on under Horizon 2020. Effectively the Grand Societal Challenge of Horizon 2020 also includes the issue of food impact in human health.

Certainly, understanding diet effects may be an instrument to favour a stable
and healthy oral and intestinal microbiota, which is able to prevent diseases
and guarantee human longevity.